The present invention is concerned with a pressurized water injection device for an apparatus for preparing a beverage from a capsule containing an extractable product.
xe2x80x9cEspressoxe2x80x9d coffee machines are already known since a number of years, which make use of capsules containing a dose of ground coffee for the preparation of a coffee beverage.
In these apparatuses, a liquid is introduced under pressure inside the capsule mounted in a housing cavity of the apparatus by means of a capsule-holder and the coffee beverage is collected at the outlet of the capsule-holder.
These coffee machines include, generally, a pump for supplying the water, a heating system for heating the water and a device for injecting the water into the capsule.
In use, a capsule is placed into a capsule-holder provided with a handle and the capsule-holder is locked onto the coffee machine via a bayonet connection system, by imparting a rotational motion to the handle, in such a manner as to position the capsule in a housing of the machine.
During this locking operation the upper side of the capsule is perforated by a protruding injection nozzle, and the bottom of the cartridge is perforated by protruding members located on the bottom of the capsule-holder as pressure is applied.
Subsequently, water is injected under pressure into the capsule by the injection device and the coffee extracted is collected in a cup placed beneath the capsule-holder.
In this type of coffee machine, the pressure of the hot water exiting from the injection nozzle can reach 16 bars such that a perfectly water-tight seal has to be established when locking the capsule-holder to the coffee machine via the bayonet connection system, which necessitates the application of a significant force on the handle of the capsule-holder, during its tightening by rotation.
This force, exerted upon the handle, generally induces a rotation of the entire machine, so that it is necessary to hold down the coffee machine with the free hand. Furthermore, it is difficult to automate the capsule loading and ejection operations with this type of system.
Furthermore, this locking can be difficult to carry out by users who lack the strength needed or who suffer a handicap of the hand.
The present invention is aimed at remedying these drawbacks, by providing a water injecting device, which does not require locking of the capsule-holder to the coffee machine by manual rotation of the handle of the capsule-holder.
The apparatus has a water injecting device including an injection head connected to a water supply conduit, a hydraulic system for displacing the injection head towards a capsule-holder positioned beneath the injection head, the hydraulic system being connected to a piston water conduit interconnected via a locking control valve to a pump, which also feeds the injection head.
The water supply conduit is connected to the injection head and is advantageously interconnected with the pump, via a valve calibrated to operate at a certain pressure, for example in the vicinity of 4 bars.
The water supply conduit can be connected to a discharge conduit via a discharge valve, to enable a release of the pressure in the injection head at the end of the beverage extraction cycle.
The locking control valve advantageously includes a position in which the piston water conduit is connected to a return conduit for enabling the release of the pressure and the discharge of the water in the hydraulic system.
The hydraulic system can include a body and a piston provided with an annular seal, enclosing a water-tight space connected with the piston water conduit.
Advantageously, the piston and the seal have a shape and a size such that, when the piston assumes a slanted position in the body, this causes a breakdown of the water-tightness and, accordingly, a release of the pressure in the hydraulic system.
The injection head includes a plurality of perforating and injecting spikes, distributed over a lower surface, for injecting water into the capsule, in the manner of a shower head.
The injection head has the general shape of a disk with a diameter such that it may be mounted slidably into the body of the hydraulic system to abut against the piston, the radial clearance between the Injection head and the body being such that the injection head can assume a slanted position at an angle which is sufficient to cause a breakdown of the water-tightness of the piston.
The plate of the injection head can be provided with a passage extending between a connector part for connecting the supply conduit, and with a space above a plate with multiple perforating and injecting spikes, for its supply with injection water.
The injection head includes attachment means to which are attached return springs which are fastened at their other end to a support frame of the water injecting device, for returning the piston and the injection head to their standby position.